1. Technical Field
The present invention relates to a recording process using an aqueous ink for performing ink jet recording on a recording medium having a non-ink-absorbing recording surface, such as plastics.
2. Related Art
In known methods for recording on non-ink-absorbing recording media, non-aqueous inks containing main components of organic solvents have been widely used. For example, as a non-aqueous ink jet ink for printing high-quality images and characters on a surface of a vinyl chloride-based resin material, such as a polyvinyl chloride sheet, which is widely used as a medium, for example, for outdoor advertisements, inks each containing a pigment excellent in light resistance, a resin component for fixing the pigment to the surface of a vinyl chloride-based resin material, and an organic solvent that can dissolve the resin component are commonly used. These non-aqueous inks are excellent in some aspects, for example, satisfactory water resistance caused by using both a water-insoluble coloring agent and a water-insoluble resin component and prevention of images from bleeding due to quick drying caused by using a highly volatile solvent. However, since an image is formed by volatilization of the solvent on the surface of a recording medium, there are problems of an odor and toxicity of the solvent during drying. Furthermore, influences of organic solvents on the environment have been concerned.
For example, JP-A-2007-291257 discloses an ink jet recording process using an ink jet ink that is a non-aqueous ink jet ink containing a relatively high-safety organic solvent and being thereby excellent in printing suitability to polyvinyl chloride (PVC), a kind of non-absorptive recording medium, emission stability, and safety and not causing a problem of odor. However, the ink contains, as an example, a main solvent of diethylene glycol diethyl ether in not less than 80 mass %, and it is therefore obvious that the safety is significantly low compared to aqueous inks. In addition, influences of the large amount of the volatile solvent on the environment are considerable. Accordingly, there is a demand for a recording process using an aqueous ink in recording on a non-ink-absorbing recording medium, such as a polyvinyl chloride sheet, from the viewpoints of safety and protection of the environment.
Against this problem, for example, JP-A-2008-260820 discloses an aqueous heat fixing ink that is an aqueous ink jet ink, gives a satisfactory high-speed printing image quality not causing defects such as spots on a non-absorptive recording medium, and can be stably used for a long time and discloses a heat fixing ink jet recording process using the ink. The amount of an organic solvent is 10 to 35 mass %, and diethylene glycol diethyl ether is mentioned as an example of the organic solvent. It is described that a combination of a specific organic solvent and a water-soluble resin and heating of the non-absorptive recording medium to 40 to 90° C. inhibit spots from occurring to give satisfactory recording image quality.
On the other hand, polyvinyl chloride causes defects, such as deformation and dimensional change due to expansion and contraction, at a temperature higher than 60° C. However, JP-A-2008-260820 does not mention abrasion resistance in heating printing at a temperature range of 40 to 60° C. in which polyvinyl chloride can be prevented from softening. Thus, in recording using an aqueous ink on a polyvinyl chloride material, an effective ink jet recording process showing abrasion resistance that is equal to that of a non-aqueous ink has not been established yet.